The present invention relates to an optical fiber array formed by fixing optical fibers in V-shaped grooves.
In recent years, due to the increasing density of optical fibers, more and more fibers are used for planar waveguides (PLC). To avoid the increase in size of waveguide elements associated with the increasing number of fibers and to further increase the density, efforts are being made to reduce the conventional standard type waveguide pitch. To account for the increasing density of optical fibers and the decreasing waveguide pitch, efforts are also being made to reduce the inter-fiber pitch of fiber arrays connected to optical fibers.
FIG. 4 shows an example of a half-pitch fiber array formed by reducing the conventional pitch down to about half.
In FIG. 4, a covered fiber housing substrate 15 is stuck and fixed to a lower substrate 10 having V-shaped grooves, from above a step section 12 of the lower substrate 10, and covered fibers 13a and 13b arranged in two stages are inserted through a covered housing groove 17 formed in the covered fiber housing substrate 15 so that the upper and lower fibers are alternately aligned in the V-shaped grooves. Then, an upper substrate (a fiber presser substrate) 11 is installed and fixed to the lower substrate 10 from above the V-shaped grooves therein to form an optical fiber array 22.
However, in the optical fiber array of the above structure, an adhesive is used to fix non-covered optical fibers and covered optical fibers between the upper and lower substrates. A large amount of adhesive, however, is filled particularly in a portion over the step section 12 in the covered housing groove 17, so stress (distortion) caused by the hardening and contraction of the adhesive cannot be neglected.